Method of making a synthetic alkylaryl sulfonate

ABSTRACT

A synthetic petroleum sulfonate prepared by a process comprising (a) reacting a first amount of at least one aromatic compound with a first amount of a mixture of olefins having from about 8 to about 100 carbon atoms, in the presence of a strong acid catalyst; (b) reacting the product of (a) with an additional amount of at least one aromatic compound and an additional amount of strong acid catalyst and, optionally, with an additional amount of a mixture of olefins selected from olefins having from about 8 to about 100 carbon atoms, in the presence of a strong acid catalyst, wherein the resulting product comprises at least about 80 weight percent of a 1,2,4-trialkylsubstituted aromatic compound; (c) sulfonating the product of (b); and (c) neutralizing the product of (b) with an alkali or alkaline earth, metal hydroxide or ammonia.

FIELD OF THE INVENTION

The present invention is directed to a method of making a syntheticalkylaryl sulfonate that is derived by sulfonating an alkylated aromaticcompound by reacting an aromatic compound with a mixture of olefinsselected from olefins having from about 8 to about 100 carbon atoms inthe presence of a strong acid catalyst, whereby the reaction takes placein two reactors in series. The alkylated aromatic compound may be usedas an enhanced oil recovery alkylate. These sulfonates exhibit superiorperformance as enhanced oil recovery surfactants.

BACKGROUND OF THE INVENTION

It is well known to catalyze the alkylation of aromatics with a varietyof Lewis or Bronsted acid catalysts. Typical commercial catalystsinclude phosphoric acid/kieselguhr, aluminum halides, boron trifluoride,antimony chloride, stannic chloride, zinc chloride, onium poly(hydrogenfluoride), and hydrogen fluoride. Alkylation with lower molecular weightolefins, such as propylene, can be carried out in the liquid or vaporphase. For alkylations with higher olefins, such as C₁₆₊ olefins, thealkylations are done in the liquid phase, often in the presence ofhydrogen fluoride. Alkylation of benzene with higher olefins may bedifficult, and typically requires hydrogen fluoride treatment. Such aprocess is disclosed by Himes in U.S. Pat. No. 4,503,277, entitled “HFRegeneration in Aromatic Hydrocarbon Alkylation Process,” which ishereby incorporated by reference for all purposes.

DESCRIPTION OF THE RELATED ART

Mikulicz et al, U.S. Pat. No. 4,225,737, discloses a process for thealkylation of an aromatic hydrocarbon with an olefin-acting alkylatingagent. The aromatic hydrocarbon is commingled with a first portion ofsaid alkylating agent in a first alkylation reaction zone at alkylationreaction conditions in contact with a hydrofluoric acid catalyst.

Boney, U.S. Pat. No. 3,953,538 discloses an alkylation process in whicha stream of an olefinic material is mixed with an acid stream andpolymerized to cause formation of a polymeric diluent for the highstrength acid which is initially charged to the alkylation process.

Mehlberg et al, U.S. Pat. No. 5,750,818 discloses a process for theliquid phase alkylation in an alkylation reactor of a hydrocarbonsubstrate with an olefinic alkylating agent in the presence of an acidalkylation catalyst at least one hydrocarbon having a lower boilingpoint than the hydrocarbon substrate and with a substantialstoichiometric excess of the hydrocarbon substrate over the alkylatingagent to form a liquid product mixture.

King et al., U.S. Pat. No. 6,551,967 discloses a low overbased alkalineearth metal alkylaryl sulfonate having a Total Base Number of from about2 to about 30, a dialkylate content of 0% to about 25% and amonoalkylate content of about 75% to about 90% or more, wherein thealkylaryl moiety is alkyltoluene or alkylbenzene in which the alkylgroup is a C₁₅-C₂₁ branched chain alkyl group derived from a propyleneoligomer are useful as lubricating oil additives.

LeCoent, U.S. Pat. No. 6,054,419 discloses a mixture of alkyl arylsulfonates of superalkalinized alkaline earth metals comprising (a) 50to 85% by weight of a mono alkyl phenyl sulfonate with a C14 to C40linear chain wherein the molar proportion of phenyl sulfonatesubstituent in position 1 or position 2 is between 0 and 13% and (b0 15to 50% by weight of a heavy alkyl aryl sulfonate, wherein the arylradical is phenyl or not, and the alkyl chains are either two linearalkyl chains with a total number of carbon atoms of 16 to 40, or one ora plurality of branched alkyl chains with on average a total number ofcarbon atoms of 15 to 48.

Malloy et al., U.S. Pat. No. 4,536,301 discloses a surfactant slug usedto recover residual oil in subterranean reservoirs. The slug comprises amixture of (1) from about 1 to about 10% of a sulfonate of a mixture ofmono- and dialkyl-substituted aromatic hydrocarbon which has beenobtained by the alkylation of art aromatic hydrocarbon with an olefinichydrocarbon in the presence of a hydrogen fluoride catalyst; (2) a loweralkyl alcohol which possesses from about 3 to about 6 carbon atoms; and(3) a nonionic cosurfactant comprising an ethoxylated n-alcohol whichpossesses from about 12 to about 15 carbon atoms.

Campbell et al., U.S. Pat. No. 6,989,355 discloses an under-neutralizedalkylxylene sulfonic acid composition for enhanced oil recoveryprocesses. This invention is also directed to a method for enhancing therecovery of oil from a subterranean reservoir which method employs theunderneutralized alkylxylene sulfonic acid compositions of the presentinvention. The under-neutralized alkylxylene sulfonic acid compositionsare employed in an aqueous media. The method optionally employs suitableco-surfactants, such as alcohols, alcohol ethers, polyalkylene glycols,poly (oxyalkylene)glycols and/or poly(oxyalkylene)glycol ethers.

Parker, U.S. Pat. No. 4,816,185 discloses reaction products C₉-C₃₀alkylbenzenes with styrene and sulfonated derivatives thereof andprocesses for preparing such products and derivatives. The sulfonatesalts of reaction products are especially useful as detergents.

SUMMARY OF THE INVENTION

In its broadest embodiment, the present invention is directed to aprocess for preparing a synthetic alkylaryl sulfonate comprising

(a) reacting a first amount of at least one aromatic compound with afirst amount of a mixture of olefins selected from olefins having fromabout 8 to about 100 carbon atoms, in the presence of a strong acidcatalyst; (b) reacting the product of (a) with an additional amount ofat least one aromatic compound and an additional amount of strong acidcatalyst and, optionally, with an additional amount of a mixture ofolefins selected from olefins having from about 8 to about 100 carbonatoms, wherein the resulting product comprises at least about 80 weightpercent of a 1, 2, 4 tri-alkylsubstituted aromatic compound; (c)sulfonating the product of (b); and (d) neutralizing the product of (c)with a source of alkali or alkaline earth metal or ammonia.

Accordingly, the present invention relates to a process for preparing asulfonated alkylated aromatic.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 discloses the alkylation process employed in the manufacture ofthe synthetic alkylaryl sulfonate of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

While the invention is susceptible to various modifications andalternative forms, specific embodiments thereof are herein described indetail. It should be understood, however, that the description herein ofspecific embodiments is not intended to limit the invention to theparticular forms disclosed, but on the contrary, the intention is tocover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the invention as defined by the appended claims.

DEFINITIONS

Olefins—The term “olefins” refers to a class of unsaturated aliphatichydrocarbons having one or more carbon-carbon double bonds, obtained bya number of processes. Those containing one double bond are calledmono-alkenes, and those with two double bonds are called dienes,alkyldienes, or diolefins. Alpha olefins are particularly reactivebecause the double bond is between the first and second carbons.Examples are 1-octene and 1-octadecene, which are used as the startingpoint for medium-biodegradable surfactants. Linear and branched olefinsare also included in the definition of olefins.

Linear Olefins—The term “linear olefins,” which include normal alphaolefins and linear alpha olefins, refers to olefins which are straightchain, non-branched hydrocarbons with at least one carbon-carbon doublebond present in the chain.

Double-Bond Isomerized Linear Olefins—The term “double-bond isomerizedlinear olefins” refers to a class of linear olefins comprising more than5% of olefins in which the carbon-carbon double bond is not terminal(i.e., the double bond is not located between the first and secondcarbon atoms of the chain).

Partially Branched Linear Olefins—The term “partially branched linearolefins” refers to a class of linear olefins comprising less than onealkyl branch per straight chain containing the double bond, wherein thealkyl branch may be a methyl group or higher, Partially branched linearolefins may also contain double-bond isomerized olefin.

Branched Olefins—The term “branched olefins” refers to a class ofolefins comprising one or more alkyl branches per linear straight chaincontaining the double bond, wherein the alkyl branch may be a methylgroup or higher.

C₁₂-C₃₀ ⁺ Normal Alpha Olefins—This term defines a fraction of normalalpha olefins wherein the carbon numbers below 12 have been removed bydistillation or other fractionation methods.

In one preferred embodiment of the present invention is a process forpreparing a synthetic alkylaryl sulfonate comprising (a) reacting afirst amount of at least one aromatic compound with a first amount of amixture of olefins selected from olefins having from about 8 to about100 carbon atoms, in the presence of a strong acid catalyst; (b)reacting the product of (a) with an additional amount of at least onearomatic compound and an additional amount of strong acid catalyst and,optionally, with an additional amount of a mixture of olefins selectedfrom olefins having from about 8 to about 100 carbon atoms, wherein theresulting product comprises at least about 85 weight percent of a 1, 2,4 tri-alkylsubstituted aromatic compound; (c) sulfonating the product,of (b); and (d) neutralizing the product of (c) with a source of alkalior alkaline earth metal or ammonia.

Aromatic Compound

At least one aromatic compound or a mixture of aromatic compounds may beused for the alkylation reaction in the present invention. Preferablythe at least one aromatic compound or the aromatic compound mixturecomprises at least one of monocyclic aromatics, such as benzene,toluene, xylene, cumene or mixtures thereof. The at least one aromaticcompound or aromatic compound mixture may also comprise bi-cyclic andpoly-cyclic aromatic compounds, such as naphthalenes, More preferably,the at least one aromatic compound or aromatic compound mixture isxylene, including all isomers (i.e., meta-, ortho- and para-), a raffmate of xylene isomerization, and mixtures thereof. Most preferably, theat least one aromatic compound is ortho-xylene.

Sources of Aromatic Compound

The at least one aromatic compound or the mixture of aromatic compoundsemployed in the present invention is prepared by methods that are wellknown in the art.

Olefins Sources of Olefins

The olefins employed in this invention may be linear, isomerized linear,branched or partially branched linear. The olefin may be a mixture oflinear olefins, a mixture of isomerized linear olefins, a mixture ofbranched olefins, a mixture of partially branched linear or a mixture ofany of the foregoing.

The olefins may be derived from a variety of sources. Such sourcesinclude the normal alpha olefins, linear alpha olefins, isomerizedlinear alpha olefins, dimerized and oligomerized olefins, and olefinsderived from olefin metathesis. Another source from which the olefinsmay be derived is through cracking of petroleum or Fischer-Tropsch wax.The Fischer-Tropsch wax may be hydrotreated prior to cracking. Othercommercial sources include olefins derived from paraffin dehydrogenationand oligomerization of ethylene and other olefins, methanol-to-olefinprocesses (methanol cracker) and the like.

The olefins may also be substituted with other functional groups, suchas carboxylic acid groups, heteroatoms, and the like, provided that suchgroups do not react with the strong acid catalyst.

The mixture of olefins is selected from olefins with carbon numbersranging from about 8 carbon atoms to about 100 carbon atoms. Preferably,the mixture of olefins is selected from olefins with carbon numbersranging from about 10 to about 80 carbon atoms, more preferred fromabout 14 to about 60 carbon atoms.

In another embodiment, preferably, the mixture of olefins is selectedfrom linear alpha olefins or isomerized olefins containing from about 8to about 100 carbon atoms. More preferably, the mixture of olefins isselected from linear alpha olefins or isomerized olefins containing fromabout 10 to about 80 carbon atoms. Most preferably, the mixture ofolefins is selected from linear alpha olefins or isomerized olefinscontaining from about 14 to about 60 carbon atoms.

Furthermore, in a preferred embodiment, the mixture of olefins containsa distribution of carbon atoms that comprises from about 40 to about 90percent C₁₂ to C₂₀ and from about 4 percent to about 15 percent C₃₂ toC₅₈. More preferably, the distribution of carbon atoms comprises fromabout 50 to about 80 percent C₁₂ to C₂₀ and from about 4 percent toabout 15 percent C₃₂ to C₅₈.

The mixture of branched olefins is preferably selected from polyolefinswhich may be derived from C₃ or higher monoolefins (i.e., propyleneoligomers, butylenes oligomers, or co-oligomers etc.). Preferably, themixture of branched olefins is either propylene oligomers or butylenesoligomers or mixtures thereof.

Normal Alpha Olefins

Preferably, the mixture of linear olefins that may be used for thealkylation reaction is a mixture of normal alpha olefins selected fromolefins having from about 8 to about 100 carbon atoms per molecule. Morepreferably the normal alpha olefin mixture is selected from olefinshaving from about 10 to about 80 carbon atoms per molecule. Mostpreferably, the normal alpha olefin mixture is selected from olefinshaving from about 12 to about 60 carbon atoms per molecule. Anespecially preferred range is from about 14 to about 60.

In one embodiment of the present invention, the normal alpha olefins areisomerized using at least one of two types of acidic catalysts, solid orliquid. A solid catalyst preferably has at least one metal oxide and anaverage pore size of less than 5.5 angstroms. More preferably, the solidcatalyst is a molecular sieve with a one-dimensional pore system, suchas SM-3, MAPO-11, SAPO-11, SSZ-32, ZSM-23, MAPO-39, SAPO-39, ZSM-22 orSSZ-20. Other possible acidic solid catalysts useful for isomerizationinclude ZSM-35, SUZ-4, NU-23, NU-87 and natural or syntheticferrierites. These molecular sieves are well known in the art and arediscussed in Rosemarie Szostak's Handbook of Molecular Sieves (New York,Van Nostrand Reinhold, 1992) which is herein incorporated by referencefor all purposes. A liquid type of isomerization catalyst that can beused is iron pentacarbonyl (Fe(CO)₅).

The process for isomerization of normal alpha olefins may be carried outin batch or continuous mode. The process temperatures may range fromabout 50° C. to about 250° C. In the batch mode, a typical method usedis a stirred autoclave or glass flask, which may be heated to thedesired reaction temperature. A continuous process is most efficientlycarried out in a fixed bed process. Space rates in a fixed bed processcan range from 0.1 to 10 or more weight hourly space velocity.

In a fixed bed process, the isomerization catalyst is charged to thereactor and activated or dried at a temperature of at least 150° C.under vacuum or flowing inert, dry gas. After activation, thetemperature of the isomerization catalyst is adjusted to the desiredreaction temperature and a flow of the olefin is introduced into thereactor. The reactor effluent containing the partially-branched,isomerized olefins is collected. The resulting partially-branched,isomerized olefins contain a different olefin distribution (i.e., alphaolefin, beta olefin; internal olefin, tri-substituted olefin, andvinylidene olefin) and branching content that the unisomerized olefinand conditions are selected in order to obtain the desired olefindistribution and the degree of branching.

Acid Catalyst

Typically, the alkylated aromatic compound may be prepared using strongacid catalysts (Bronsted or Lewis acids). The term “strong acid” refersto an acid having a pK_(a) of less than about 4. The term “strong acid”is also meant to include mineral acids stronger than hydrochloric acidand organic acids having a Hammett acidity value of at least minus 10 orlower, preferably at least minus 12 or lower, under the same conditionsemployed in context with the herein described invention. The Hammettacidity function is defined as:

H_(o)=pK_(BH+)−log(BH⁺/B)

where B is the base and BH⁺ its protonated form, pK_(BH+) is thedissociation constant of the conjugate acid and BH⁺/B is the ionizationratio; lower negative values of H_(o) correspond to greater acidstrength.

Preferably, the strong acid catalyst is selected from a group consistingof hydrochloric acid, hydrofluoric acid, hydrobromic acid, sulfuricacid, perchloric acid, trifluoromethane sulfonic acid, fluorosulfonicacid, and nitric acid. Most preferred, the strong acid catalyst ishydrofluoric acid.

The alkylation process may be carried out in a batch or continuousprocess. The strong acid catalyst may be recycled when used in acontinuous process. The strong acid catalyst may be recycled orregenerated when used in a batch process or a continuous process.

The strong acid catalyst may be regenerated after it becomes deactivated(i.e., the catalyst has lost all or some portion of its catalyticactivity). Methods that are well known in the art may be used toregenerate the deactivated hydrofluoric acid catalyst.

Process for Preparing Alkylated Aromatic Compound

In one embodiment of the present invention, the alkylation process iscarried out by reacting a first amount of at least one aromatic compoundor a mixture of aromatic compounds with a first amount of a mixture ofolefin compounds in the presence of a strong acid catalyst, such ashydrofluoric acid, in a first reactor in which agitation is maintained,thereby producing a first reaction mixture. The resulting first reactionmixture is held in a first alkylation zone under alkylation conditionsfor a time sufficient to convert the olefin to aromatic alkylate (i.e.,a first reaction product). After a desired time, the first reactionproduct is removed from the alkylation zone and fed to a second reactorwherein the first reaction product is reacted with an additional amountof at least one aromatic compound or a mixture of aromatic compounds andan additional amount of strong acid catalyst and, optionally, with anadditional amount of a mixture of olefin compounds wherein agitation ismaintained. A second reaction mixture results and is held in a secondalkylation zone under alkylation conditions for a time sufficient toconvert the olefin to aromatic alkylate (i.e., a second reactionproduct). The second reaction product is fed to a liquid-liquidseparator to allow hydrocarbon (i.e., organic) products to separate fromthe strong acid catalyst. The strong acid catalyst may be recycled tothe reactor(s) in a closed loop cycle. The hydrocarbon product isfurther treated to remove excess un-reacted aromatic compounds and,optionally, olefinic compounds from the desired alkylate product. Theexcess aromatic compounds may also be recycled to the reactor(s).

In another embodiment of the present invention, the reaction takes placein more than two reactors which are located in series. Instead offeeding the second reaction product to a liquid-liquid separator, thesecond reaction product is fed to a third reactor wherein the secondreaction product is reacted with an additional amount of at least onearomatic compound or a mixture of aromatic compounds and an additionalamount of strong acid catalyst and, optionally, with an additionalamount of a mixture of olefin compounds wherein agitation is maintained.A third reaction mixture results and is held in a third alkylation zoneunder alkylation conditions for a time sufficient to convert the olefinto aromatic alkylate (i.e., a third reaction product). The reactionstake place in as many reactors as necessary to obtain the desiredalkylated aromatic reaction product.

The total charge mole ratio of hydrofluoric acid to the mixture ofolefin compounds is about 1.0 to 1 for the combined reactors.Preferably, the charge mole ratio of hydrofluoric acid to the mixture ofolefin compounds is no more than about 0.7 to 1 in the first reactor andno less than about 0.3 to 1 in the second reactor.

The total charge mole ratio of the aromatic compound to the mixture ofolefin compounds is about 7.5 to 1 for the combined reactors.Preferably, the charge mole ratio of the aromatic compound to themixture of olefin compounds is no less than about 1.4 to 1 in the firstreactor and is no more than about 6.1 to 1 in the second reactor.

Many types of reactor configurations may be used for the reactor zone.These include, but are not limited to, batch and continuous stirred tankreactors, reactor riser configurations, ebulating bed reactors, andother reactor configurations that are well known in the art. Many suchreactors are known to those skilled in the art and are suitable for thealkylation reaction. Agitation is critical for the alkylation reactionand can be provided by rotating impellers, with or without baffles,static mixers, kinetic mixing in risers, or any other agitation devicesthat are well known in the art.

The alkylation process may be carried out at temperatures from about 0°C. to about 100° C. The process is carried out under sufficient pressurethat a substantial portion of the feed components remain in the liquidphase. Typically, a pressure of 0 to 150 psig is satisfactory tomaintain feed and products in the liquid phase.

The residence time in the reactor is a time that is sufficient toconvert a substantial portion of the olefin to alkylate product. Thetime required is from about 30 seconds to about 30 minutes. A moreprecise residence time may be determined by those skilled in the artusing batch stirred tank reactors to measure the kinetics of thealkylation process.

The at least one aromatic compound or mixture of aromatic compounds andthe mixture of olefins may be injected separately into the reaction zoneor may be mixed prior to injection. Both single and multiple reactionzones may be used with the injection of the aromatic compounds and themixture of olefins into one, several, or all reaction zones. Thereaction zones need not be maintained at the same process conditions.

The hydrocarbon feed for the alkylation process may comprise a mixtureof aromatic compounds and a mixture olefins in which the molar ratio ofaromatic compounds to olefins is from about 0.5:1 to about 50:1 or more.In the case where the molar ratio of aromatic compounds to olefin is >1.0 to 1, there is an excess amount of aromatic compounds present.Preferably an excess of aromatic compounds is used to increase reactionrate and improve product selectivity. When excess aromatic compounds areused, the excess un-reacted aromatic in the reactor effluent can beseparated, e.g. by distillation, and recycled to the reactor.

Tri-Alkylsubstituted Alkylated Aromatic Compound

An intermediate product of the presently claimed invention is atri-alkylsubstituted alkylated aromatic compound. Preferably, theresulting intermediate product comprises at least about 80 weightpercent of a 1, 2, 4 tri-alkylsubstituted aromatic compound. Morepreferred, the resulting product comprises at least about 85 weightpercent, even more preferred at least about 90 weight percent of a 1, 2,4 tri-alkylsubstituted aromatic compound.

Other embodiments will be obvious to those skilled in the art.

The following examples are presented to illustrate specific embodimentsof this invention and are not to be construed in any way as limiting thescope of the invention.

Preparation of Alkylaryl Sulfonate

In one embodiment, of the present invention, the product prepared by theprocess described herein (i.e., alkylated aromatic compound: 1,2,4tri-alkylsubstituted alkylbenzene; 1,2,3 tri-alkylsubstitutedalkylbenzene and mixtures thereof) is further reacted to form asulfonate.

Sulfonation

Sulfonation of the alkylaryl compound may then be performed by anymethod known to one of ordinary skill in the art. The sulfonationreaction is typically carried out in a continuous falling film tubularreactor maintained at about 55° C. The alkylaryl compound is placed inthe reactor along with the sulfur trioxide diluted with air, sulfuricacid, chlorosulfonic acid or sulfamic acid, thereby producing alkylarylsulfonic acid. Preferably, the alkylaryl compound is sulfonated withsulfur trioxide diluted with air. The charge mole ratio of sulfurtrioxide to alkylate is maintained at about 0.8 to 1.1:1.

Neutralization of Alkylaromatic Sulfonic Acid

Neutralization of the alkylaryl sulfonic acid may be carried out in acontinuous or batch process by any method known to a person skilled inthe art to produce alkylaryl sulfonates. Typically, an alkylarylsulfonic acid is neutralized with a source of alkali or alkaline earthmetal or ammonia. Preferably, the source is an alkali or alkaline earthmetal; more preferably, the source is an alkaline earth metal hydroxide,such as but not limited to, calcium hydroxide or magnesium hydroxide.

Other embodiments will be obvious to those skilled in the art.

The following examples are presented to illustrate specific embodimentsof this invention and are not to be construed in any way as limiting thescope of the invention.

EXAMPLES Examples 1-3 Alkylation of Ortho-Xylene with C₁₄₋₃₀₊ NAO UsingTwo Alkylation Reactors in Series

The alkylated ortho-xylenes of Examples 1-3 were prepared in acontinuous alkylation pilot plant using hydrofluoric acid (HF) in whichtwo alkylation reactors (1.15 liter volume each) were in series followedby a 25 liter settler to separate the organic phase from the HF phase.All equipment was maintained under a pressure of 5 bar and the reactorsand settler were jacketed to allow temperature control. In addition, thealkylation reactors were configured such that the ortho-xylene, normalalpha olefins (NAO) and HF could be fed to each reactor at a specifiedrate.

TABLE 1 Example Reaction Conditions 1 2 3 Reactor 1 HF/Olefin Vol. Ratio0.7 0.7 0.7 Xylene/Olefin CMR 1.4 1.4 1.4 Temperature (° C.) 64 70 70Reactor 2 HF/Olefin Vol. Ratio 1 1 1 Xylene/Olefin CMR 7.5 7.5 7.5Temperature (° C.) 60 60 60 * The CMR in Reactor is the cumulativeratio, which includes Reactor 1 reactants.

Following the settler, the organic phase was removed through a valve andallowed to expand to atmospheric pressure. The HF acid phase wasseparated. The resulting organic phase was then distilled under vacuumto remove the excess ortho-xylene. Results are shown in Table 1.

The alkylation feedstock consisted of a mixture of o-xylene and C₁₄-C₃₀⁺ normal alpha olefins with a molar ratio of xylene/olefin=7.5. Theolefin used to make this feed was a blend of commercial C₁₄-C₃₀₊ cuts.The distribution of olefins in the feed is shown in Table 2.

TABLE 2 Olefin Feedstock Distribution Carbon Number Wt - % 14 24.4 1618.4 18 15.2 20 9.7 22 8.2 24 5.7 26 5.4 28 5.0  30+ 8.0

The feed mixture was stored under dry nitrogen during use. Because ofthe waxy nature of the alpha olefin, the alkylation feed mixture washeated to 50° C. to keep all the olefin in solution. O-Xylene was alsostored under dry nitrogen during use.

Examples 4-7 General Procedure for Sulfonation and Neutralization ofAlkyl Ortho-Xylene Alkylate

Sulfonation of the alkylxylene was performed in a continuous fallingfilm flow reactor by contacting the alkylxylene with a stream of air andsulfur trioxide. The molar ratio of the alkylxylene to sulfur trioxideranged from was about 1. Detailed values are given in Table 3. Thereactor jacket was maintained around 60° C. The sulfonic acid productwas titrated potentiometrically with a standardized cyclohexylaminesolution to determine the weight percent of the sulfonic acid (as HSO₃)and the sulfuric acid (H₂SO₄) in the samples, Results are shown in Table3.

The resulting alkyl ortho-xylene sulfonic acids were converted to theircorresponding sodium salt by treatment with one equivalent of aqueousNaOH (50% aqueous NaOH solution). The salts were evaluated by the FreshInterfacial Tension (FIT) Method. This procedure was as follows:

-   -   1) A 3.0 wt % stock solution of alkyl ortho-xylene sodium        sulfonate was prepared in distilled water;    -   2) A stock solution of 3.0 wt % co-solvent (diethylene glycol        n-butyl ether) and stock 3.0 wt-% sodium chloride solution in        distilled water were prepared;    -   3) The alkyl ortho-xylene sodium stock sulfonate solution and        stock solution of co-solvent/sodium chloride were blended to        achieve the appropriate salinity (0.1, 0.2, 0.3, 0.4, 0.5 wt %        sodium chloride) and constant concentration of the sodium        sulfonate and co-solvent.

All samples contained 0.2 wt % alkyl ortho-xylene sodium sulfonate and0.067 wt % co-solvent (weight ration 3/1 of sodium sulfonate:co-solvent).

To measure the interfacial tension, the sodium sulfonate/co-solventsolutions were each placed in the capillary of a Temco Model 501Tensiometer followed by approximately 2 μl of Minas crude oil(pre-heated so to be well above its Wax Appearance Temperature (WAT)).The samples were heated to 200° F., spun in the Tensiometer at two orthree rotation speeds (300, 500 and sometimes 8000 rpm), and their dropgeometries measured over 1-3 hours. The FIT measure at the differentspeeds and generally good agreement was observed between the differentmeasurements. Rotation speed was adjusted in some cases to achieve anoil drop geometry with an aspect ratio of length/width of 4 or greaterand allowed to expand to atmospheric pressure.

Table 4 summarizes the FIT measurements of the alkyl ortho-xylene sodiumsulfonates. Without surfactant, FIT measurements for Minas crude are onthe order of 10-20 dynes/cm. FIT measurements for the alkyl ortho-xylenesodium sulfonates of this invention are all less than 0.01 dynes/cm.Such surfactants are considered to be useful in recovering oil in lowsalinity reservoirs. Optimal salinity is the salinity where theinterfacial tension is lowest, which in Examples 4-7 is 0.2% NaCl.

TABLE 3 Properties of ortho-Xylene Alkylates Prepared by HydrofluoricAcid Catalyzed Alkylation Relative % Relative % Aromatic Ring AromaticRing % Alkyl Chain Attachment* Attachment % Attachment % 2− 3− 4− 4+Example 1, 2, 3 1, 2, 4− ArylAlkane ArylAlkane ArylAlkane ArylAlkane 111.0 89.0 11 10 15.6 63.4 2 13.0 87.0 12.4 10.7 16.0 60.9 3 10.0 90.011.2 11.1 15.5 62.2 *% Alkyl Chain Attachment refers to the carbonnumber along the alkyl chain to which the aromatic ring is attached.

TABLE 4 Properties of the Alkyl ortho-Xylene Sulfonic Acids and the FITResults of the Alkyl ortho-Xylene Sodium Sulfonates (Corresponding toTable 3) FIT Alkylate CMR Sulfonic Acids Optimal Example Example No.SO₃/Alkylate % RSO_(3 as) HSO3 % H2SO₄ Dynes/cm Salinity, % NaCl 4 10.98 15.2 0.67 0.0070 0.2 5 1 1.02 17.1 0.56 0.0009 0.2 6 3 0.98 15.61.20 0.0010 0.2 7 2 1.05 16.2 0.97 0.0030 0.2

Example 8 Infrared Method to Determine Relative Percentage of 1, 2, 3Alkyl and 1, 2, 4-Alkyl Aromatic Ring Attachment

The infrared spectrum of a sample of alkylated ortho-xylene product wasobtained using an Infrared spectrometer (Thermo model 4700) equippedwith a rebounce diamond attenuated reflectance cell. The absorbancespectrum of the sample between 600 and 1000 cm⁻¹ was displayed and thepeaks at about 780, 820, and 880 cm⁻¹ were integrated. The relativepercentage area of each peak was calculated and the percent 1, 2,3-alkyl aromatic content is represented by the relative area percentageof the 780 cm⁻¹ peak.

Example 9 Carbon Nuclear Magnetic Resonance Method to Determine thePercent Alkyl Attachment Position to the Aromatic Ring

Quantitative ¹³C NMR spectra were obtained on a 300 MHz Varian GeminiNMR (75 MHz carbon) using about 1.0 g of sample dissolved in about 3.0mL of 0.5 M chromium (acac)₃ in chloroform-d contained in a 10 mm NMRtube. The transmitter pulse sequence (delay (2.2 s), 90 pulseacquisition (0.853 s) was employed with the decoupler (WALTZ-16) gatedoff during the delay and on during acquisition. Cursory examination ofthe T1's for the quaternary carbons at our CR(acac)₃ levels indicatedthey were about 0.4-0.5 s. Thus, the relaxation delay was always morethan four times the longest T1. We believe this is sufficient to allowresidual NOE to die away between pulse excitations even though thedecoupler duty cycle is above the recommended 5-10% range forquantitative experiments. Integration of the ¹³C NMR spectrum wascarried out with no base-line correction.

The integrated peak intensity for the quarternary carbons (Q) on thearomatic ring carbons substituted with the long chain g alkyl group andthe methane (benzylic) carbons (M) of the long chain alkyl groups wherethe long chain alkyl group is attached to the aromatic ring are used tocalculate the percent alkyl attachment position. For the different alkylchain attachments, the following assignments were made (in ppm downfieldfrom TMS): 2-position (R=Methyl); Q=145.475 ppm, M=39.56 ppm; 3-position(R=Ethyl), Q=143.502 ppm, M=47.50 ppm; 4-position (R=n-Propyl), Q=143.86ppm, M=45.4 ppm; 5-position and higher (R=greater than, n-Propyl),Q=143.86, M=45.69 ppm. The NMR spectrum is integrated and the signalsbetween 143 to 147 ppm, and 39 to 48 ppm are enlarged and integrated.For the 143 to 147 ppm region integral, the relative amount of R=Methyl,R=Ethyl and R=n-Propyl were determined. For the 39-48 ppm regionintegral, one obtains the relative amounts of R=Methyl, R=Ethyl,R=n-Propyl and R>n-Propyl. To perform the calculations, first, check tosee that the integrals for each aromatic carbon is the same. Sum theintegrals for each of the Q and M peaks and calculate the percentageattachment, from both the aromatic quarternary (Q) and aliphatic methine(M) integrals of the assigned peaks. For example, the amount of2-attachment from the integration of the aromatic quaternary carbonswould equal the integral for the 145.475 ppm signal divided by the totalof the integrals for the 145.475 ppm peak plus the integral for the143.502 ppm peak plus the integral for the 143.86 ppm peak. Thealiphatic methine carbons provide the 2-, 3-, 4, and >4-alkyl attachmentwhile the aromatic quaternary carbons provide only the 2-, 3-, and4-alkyl attachment values. The attachment values determined by thealiphatic methine and the aromatic quaternary carbons agree reasonablywell.

1. A synthetic petroleum sulfonate compound prepared by (a) reacting afirst amount of at least one aromatic compound with an amount of amixture of olefins selected from olefins having from about 8 to about100 carbon atoms, in the presence of a strong acid catalyst; (b)reacting the product of (a) with an additional amount of at least onearomatic compound and an additional amount of strong acid catalyst and,optionally, with an additional amount of a mixture of olefins selectedfrom olefins having from about 8 to about 100 carbon atoms, wherein theresulting product comprises at least about 80 weight percent, of a 1, 2,4 tri-alkyl substituted aromatic compound; (c) sulfonating the productof (b); and (d) neutralizing the product of (c) with a source of alkalior alkaline earth metal or ammonia.
 2. The synthetic petroleum sulfonateprepared by a process according to claim 1 wherein the product of (b)further comprises 1, 2, 3 tri-alkylsubstituted aromatic compound ormixtures thereof
 3. The synthetic petroleum sulfonate prepared by aprocess according to claim 1 wherein the source of alkali or alkalineearth metal is hydroxide.
 4. The synthetic petroleum sulfonate preparedby a process according to claim 1 wherein sulfonating the product occurswhen the product of (b) is reacted with sulfur trioxide which has beendiluted with air.
 5. The synthetic petroleum sulfonate prepared by aprocess according to claim 1 wherein the at least one aromatic compoundis selected from unsubstituted aromatic compounds, monosubstitutedaromatic compounds, and disubstituted aromatic compounds.
 6. Thesynthetic petroleum sulfonate prepared by a process according to claim 1wherein the mixture of olefins in step (a) or step (b) is a mixture oflinear olefins, a mixture of linear isomerized olefins, a mixture ofbranched olefins, a mixture of partially branched olefins, or a mixturethereof.
 7. The synthetic petroleum sulfonate prepared by a processaccording to claim 6 wherein the mixture of olefins in step (a) or step(b) is a mixture of linear olefins.
 8. The synthetic petroleum sulfonateprepared by a process according to claim 7 wherein the mixture of linearolefins is a mixture of normal alpha olefins.
 9. The synthetic petroleumsulfonate prepared by a process according to claim 8 wherein the mixtureof linear olefins comprises olefins derived through cracking ofpetroleum wax or Fischer Tropsch wax.
 10. The synthetic petroleumsulfonate prepared by a process according to claim 9 wherein the FischerTropsch wax is hydrotreated before cracking.
 11. The synthetic petroleumsulfonate prepared by a process according to claim 6 wherein the mixtureof olefins comprises from about 8 carbon atoms to about 100 carbonatoms.
 12. The synthetic petroleum sulfonate prepared by a processaccording to claim 11 wherein the mixture of olefins is derived fromlinear alpha olefins or isomerized olefins containing from about 8 to100 carbon atoms.
 13. The synthetic petroleum sulfonate prepared by aprocess according to claim 12 wherein the mixture of olefins is derivedfrom linear alpha olefins or isomerized olefins containing from about 10to about 80 carbon atoms.
 14. The synthetic petroleum sulfonate preparedby a process according to claim 13 wherein the mixture of olefins isderived from linear alpha olefins or an isomerized olefins containingfrom about 14 to about 60 carbon atoms.
 15. The synthetic petroleumsulfonate prepared by a process according to claim 7 wherein the mixtureof linear olefins is a mixture of linear internal olefins which havebeen derived from olefin metathesis.
 16. The synthetic petroleumsulfonate prepared by a process according to claim 1 wherein the mixtureof olefins is a mixture of branched olefins.
 17. The synthetic petroleumsulfonate prepared by a process according to claim 16 wherein themixture of branched olefins comprises polyolefin compounds derived fromC₃ or higher monoolefins.
 18. The synthetic petroleum sulfonate preparedby a process according to claim 17 wherein the polyolefin compound iseither polypropylene or polybutylene.
 19. The synthetic petroleumsulfonate prepared by a process according to claim 18 wherein thepolyolefin compound Is polypropylene.
 20. The synthetic petroleumsulfonate prepared by a process according to claim 19 wherein thepolyolefin compound is polybutylene.
 21. The synthetic petroleumsulfonate prepared by a process according to claim 1 wherein the strongacid catalyst is hydrofluoric acid.
 22. The synthetic petroleumsulfonate prepared by a process according to claim 1 wherein thereaction takes place in a continuous process.
 23. The syntheticpetroleum sulfonate prepared by a process according to claim 1 wherein,in step (b), the product of step (a) is reacted with an additionalamount of at least one aromatic compound and an additional amount of amixture of olefins selected from olefins having from about 8 to about100 carbon atoms.
 24. The synthetic petroleum sulfonate prepared by aprocess according to claim 1 wherein the resulting product comprises atleast about 85 weight percent of a 1, 2, 4, tri-alkylsubstitutedaromatic compound.